Chimera comprising bacterial cytotoxin and methods of using the same
This invention provides, a recombinant polypeptide encoding a chimera. The chimera includes a DNase I fragment or a homologue thereof and a Cdt fragment or a homologue thereof. Further, the invention provides methods, utilizing the recombinant polypeptide encoding the chimera, such as a method for inhibiting the proliferation of a neoplastic cell, a method for treating a neoplastic disease in a human subject, a method for inhibiting or suppressing a neoplastic disease in a human subject, and a method for reducing the symptoms associated with a neoplastic disease in a human subject.
1. A recombinant polypeptide comprising a chimera, wherein said chimera comprises a DNase I fragment or a homologue thereof and a cytolethal distending toxin (Cdt) fragment or a homologue thereof, wherein said Cdt fragment is a CdtB fragment, and wherein said DNase I fragment comprises the amino acid sequence set forth in SEQ ID NO.: 12, 14, or 16 and said CdtB fragment comprises the amino acid sequence set forth in SEQ ID NO.: 4, 5, 6, or 7.
2. The recombinant polypeptide of claim 1 , wherein said CdtB fragment comprises a mutation.
3. The recombinant polypeptide of claim 2 , wherein said mutation is G55R, L62E, S99Y, R100E, V134R, Y174P or their combination.
4. The recombinant polypeptide of claim 2 , wherein said DNase I fragment comprises a substitution of SEQ ID NO: 58 for SEQ ID NO: 59.
5. The recombinant polypeptide of claim 1 , wherein said chimera is His 6 -tagged.
6. The recombinant polypeptide of claim 1 , wherein said chimera comprises (a) said CdtB fragment in the amino terminus of said chimera and said DNase I fragment in the carboxy terminus of said chimera or (b) a homologue of a DNase I fragment in the carboxy terminus of said chimera and a Cdt fragment in the amino terminus of said chimera or (c) a DNase I in the carboxy terminus of said chimera and a homologue of a Cdt fragment in the amino terminus of said chimera or (d) a homologue of a DNase I fragment in the carboxy terminus of said chimera and a homologue of a Cdt fragment in the amino terminus of said chimera.
7. The recombinant polypeptide of claim 1 , wherein said recombinant polypeptide binds both CdtA and CdtC.
8. The recombinant polypeptide of claim 1 , wherein said recombinant polypeptide inhibits proliferation of a neoplastic cell.
9. The recombinant polypeptide of claim 1 , wherein said recombinant polypeptide inhibits proliferation of a neoplastic cell and binds both CdtA and CdtC.
10. A method for inhibiting the proliferation of a neoplastic cell comprising the step of contacting said cell with a recombinant polypeptide according to claim 1 or a nucleic acid molecule encoding the same, thereby inhibiting the proliferation of a neoplastic cell.
11. A recombinant polypeptide comprising a chimera, wherein said chimera comprises a DNase I fragment or a homologue thereof and a cytolethal distending toxin (Cdt) fragment or a homologue thereof, wherein the amino acid sequence of said chimera is selected from the group consisting of amino acid sequences as set forth in SEQ ID NOs: 24-27 and SEQ ID NO: 29.
12. The recombinant polypeptide of claim 11 , wherein the amino acid sequence of said recombinant polypeptide is as set forth in SEQ ID NO: 29.
13. A method for inhibiting the proliferation of an oral squamous cell carcinoma cell comprising the step of contacting said cell with a recombinant polypeptide according to claim 11 or a nucleic acid molecule encoding the same, thereby inhibiting the proliferation of said cell.